1. Field of the Invention
The present invention relates generally to a fabric for a zipper mounted thereon and, more particularly to a warp knitted fabric that has a specific portion capable of extension along a transverse direction.
2. Description of the Related Art
A conventional zipper is stitched on two fabrics and the fabrics are stitched on clothing, bag or the like. Conventional fabrics, which are made of chemical fibers, have a weak flexibility such that the fabrics have a weak capacity to sustain the transverse extension force, which is the force exerted on the fabrics along an orientation substantially perpendicular to the elongated orientation, while the zipper has been zipped. The fabrics might be torn or the zipper might be broken while such transverse force is exerted.
There are several solutions for the aforesaid problem, such as the fabric is provided with an enhancement region, which is made of strengthened fabrics, to increase the capacity of the fabric sustaining the transverse extension force. Such fabric is thicker and harder. The second way is to provide a fabric made of woofs. The woofs are made of chemical fabric having a little flexibility. Such fabric has drawbacks of not enough flexibility and fatigue of the chemical fabric after a long time of extension. The third way is to stitch a buffer region on the fabric which the buffer region is made of flexible fabric. The buffer region absorbs a part of the transverse extension force but it is harder for fabrication and the cost of fabrication is higher.
The primary object of the present invention is to provide a warp knitted fabric for a zipper mounted thereon, which is softer and has comfortable feeling.
The secondary object of the present invention is to provide a warp knitted fabric for a zipper mounted thereon, which has a well flexibility along the transverse orientation.
To achieve these objects of the present invention, a warp knitted fabric comprises a base fabric having first threads, second threads and third threads, wherein the first threads are extended along a warp-wise orientation of the base fabric to form wales and are lapped to form crochets on the base fabric, the second threads are extended along the warp-wise orientation of the base fabric and are repeatedly and cross lapped over two of the wales and the third threads are extended along the warp-wise orientation of the base fabric and are repeatedly and cross lapped over two of the wales, wherein distances of the third threads lapped are greater than distances of the second threads lapped; wherein the base fabric has a rare portion, which is a region of the base fabric having less of the third threads than the other region thereof, wherein the rare portion is arranged at between two of the wales and is extended along the warp-wise orientation of the base fabric; wherein the base fabric further has at least a fourth thread, which is made of a material with a well elasticity, wherein the fourth thread is extended along the warp-wise orientation of the base fabric and is cross lapped over two of the wales to form an elastic portion extended the warp-wise orientation of the base fabric, wherein the elastic portion has a well elasticity for tension and the elastic portion has a side overlapped with a portion of the base fabric on which the third threads are knitted to form an overlapped portion, which makes the elastic portion coupled with the base fabric firmly, and the overlapped portion has a width smaller than or substantially equal to a distance between two of the wales.